The present invention relates to liquid atomizer pumps. In particular, the invention relates to small hand-held, finger-operated dispensers involving pump assemblages as distinguished from pressurized aerosol containers and valves.
Pumps of the type with which the present invention is concerned include a piston arranged to be driven into the pump housing against a spring pressure so as to deliver the liquid to the nozzle. It is known that, in order to obtain the highest possible degree of atomization, it is preferable to provide at the pump outlet a so-called turbulence nozzle.
However, it has been found that even the use of a nozzle of this type in prior art atomizing pumps does not completely preclude the occurrence of an insufficient atomization and the formation of droplets in the vicinity of the nozzle, particularly when the pump is subjected to a relatively slow depression movement. Furthermore, the liquid remaining in the nozzle after the atomization operation tends to dry up and to obstruct the nozzle.
U.S. Pat. No. Re. 28,366, reissued Mar. 18, 1975 to Pechstein discloses an atomizing pump which has as its object the elimination of some of these drawbacks. The Pechstein patent discloses a pump that has a first piston and a second piston, the first piston having a liquid flow passage. A valve which moves relative to the first piston and the second piston is disposed for closing the liquid flow passage in the first piston.